In the manufacture of semiconductor devices, liquid crystal display devices, CCDs and other image-capture devices, plasma display devices, thin film magnetic heads, and other electronic devices (hereafter severally called “electronic devices”), an exposure apparatus is employed to project image of a fine pattern formed on a photomask or a reticle (hereafter “reticle”) onto a semiconductor wafer, a glass plate or similar (hereafter “wafer”) onto which a photoresist or other photosensitive material has been applied, to perform exposure. At this time, the reticle and wafer must be positioned (aligned) with high precision, and the pattern of the reticle must be superposed onto the pattern of the wafer with high precision. In recent years, there has been rapid progress toward finer pattern and higher integration density, and so ever-higher exposure precision has come to be demanded from such exposure apparatus. For this reason, ever stricter demands have been imposed on alignment precision as well, and higher alignment precision is sought.
In the conventional art, wafer position measurement has been performed by measuring the position of a positioning mark (alignment mark) formed on the wafer. As the alignment system used to measure the position of these alignment mark, for example, an off-axis alignment sensor of a FIA (Field Image Alignment) system, which irradiates the mark using light of broad wavelength band using a halogen lamp or similar as a light source, capturing the reflected light with a CCD camera or similar, and performing image processing of the image data of alignment mark thus obtained to measure mark position, are well known. By means of the alignment sensor of such the FIA system, thin film interference by the resist layer does not easily influence the result, and the position of an aluminum mark, an asymmetrical mark and similar can also be detected with high precision. Methods have also been disclosed enabling image capture of mark with high contrast by selecting the wavelength of the detection light (see for example Patent Reference 1) and for detecting with high precision the position even of mark with small step height using the light reflected from the mark, by emphasizing change in the detection light (see for example Patent Reference 2); and various methods have been proposed for performing alignment with higher precision.
However, when for example positioning the wafer and shot areas, the positions in the X-axis direction and Y-axis direction of each of a plurality of prescribed marks on the same wafer are measured, and based on the results EGA computations are for example performed to finally obtain the position information for control. That is, in a series of alignment processing (mark measurement processing), it is often the case that a plurality of position measurement processing operations (measurement processes for a plurality of marks) are normally performed. However, in alignment measurement methods of the conventional art, during a series of alignment measurement processing operations for the same wafer, only a single set of measurement conditions, set in advance, is applied to a plurality of objects for measurement (marks) when performing measurement processing. That is, appropriate measurement conditions have not been set for each measurement object to perform position measurements or similar.
More specifically, when for example a plurality of marks are formed in different layers on a wafer, or when the measurement precision (alignment precision) required is different for each measurement axis direction, there may be cases in which the optimum measurement conditions are different for each measurement object (mark). However, in measurement methods of the conventional art, measurements are performed under a single set of measurement conditions when performing a series of measurement processing operations, so that measurements may not have been performed under optimum conditions for each of the measurement objects (marks). If measurement conditions were to be modified for each measurement object, such problems as a considerable worsening of throughput, or adverse effects on the measurement precision accompanying fluctuations in the baseline value, or similar would result, and so measurement under such optimum conditions have in effect not been possible.    Patent Reference 1: Japanese Unexamined Patent Application, First Publication No. 2002-170757    Patent Reference 2: Japanese Unexamined Patent Application, First Publication No. H09-134863